The present invention relates to buck regulator circuits and particularly to such a regulator circuit exhibiting enhanced efficiency of operation.
In buck regulator circuits a current is supplied from a first source to a current sustaining inductance through a first switching means on a duty cycle basis for controlling an output voltage level. Second switching means, alternatively operable with the first switching means, completes a current path through the inductance when the first switching means is turned off.
In the conventional buck regulator circuit, the first switching means comprises a series pass translator. It is usually necessary to provide a substantial amount of base drive to this pass transistor, e.g. via a drive transistor, and in order that current from the drive transistor may ultimately add to the output, some form of Darlington circuit configuration is frequently used. However, the Darlington configuration prevents the pass transistor from saturating and therefore introduces an additional voltage drop across the pass transistor which translates into a considerable power loss when the output current is on the order of amps.